Third generation partnership project (3GPP) mobile communication systems based on a wideband code division multiple access (WCDMA) radio access technology are widely spread all over the world. High-speed downlink packet access (HSDPA) that can be defined as a first evolutionary stage of WCDMA provides 3GPP with a radio access technique that is highly competitive in the mid-term future. However, since requirements and expectations of users and service providers are continuously increased and developments of competing radio access techniques are continuously in progress, new technical evolutions in 3GPP are required to secure competitiveness in the future. Reduction of cost per bit, increase of service availability, flexible use of frequency bands, simple structure and open interface, proper power consumption of a user equipment (UE), and the like are defined as requirements.
Similarly to a conventional cell broadcast service (CBS), a multimedia broadcast/multicast service (MBMS) simultaneously transmits a data packet in the same manner to a plurality of users. The CBS is a low-speed message-based service whereas the MBMS aims at high-speed multimedia data transmission. The CBS is not based on an Internet protocol (IP) whereas the MBMS is based on IP multicast. If users satisfying a specific level exist in the same cell, necessary resources (or channels) transmitted to each user are shared so that a plurality of users can receive the same multimedia data. Therefore, the MBMS has an advantage in that radio resources can be more efficiently used and a multimedia service can be used at a low price from the perspective of the users.
The MBMS uses a common channel so that a plurality of user equipments (UEs) effectively receive one service. That is, regarding data of one service, only one common channel is allocated instead of allocating a predetermined number of dedicated channels corresponding to the plurality of UEs which intend to receive the service in one cell. Since the plurality of UEs simultaneously receive the common channel, efficiency of radio resources increases.
For the effective use of the radio resources, the MBMS uses a method in which one common channel is received by a plurality of UEs. That is, in every transmission period, when transmission of MBMS data is instructed, the plurality of UEs attempt to receive the MBMS data through the common channel.
However, the plurality of UEs may belong to different radio channel environments. A base station (BS) neither allocates the common channel nor controls transmission characteristics according to a location of each UE or a radio channel environment. That is, even if the UE fails to receive the MBMS data or if the UE is located in a poor radio channel environment, the BS cannot perform a special operation for the UE. Therefore, the UE experiences deterioration in service quality.